Weighing modules are commonly incorporated into conveyor systems for handling mailed parcels or packages for various purposes, such as determining whether the item is too heavy for subsequent processing and needs to be diverted. Weighing of flat mail (letters and flats) is less easy to accomplish within a letter sorting process because letters are conveyed at high speed in most automated sorting machines.
Schererz et al. U.S. patent application Ser. No. 09/969,274, filed Oct. 2, 2001, Pub. No. 20020070149, Jun. 13, 2002, describes a mixed mail sorting machine wherein a feeder receives a stack of incoming mail pieces and outputs the mail pieces one at a time in a vertical position. A scanner receives mail pieces from the feeder and scans each mail piece in a vertical position to read sorting information thereon. A transport device turns the mailing through a 180 degree arc, and then a reorientation conveyor receives the scanned mail pieces from the scanner and re-orients each mail piece from a vertical to a horizontal position. Mail passes to a splitter conveyor including a movable divert section which diverts each mail piece to an upper path or a lower path. A bin module which includes upper and lower bin sections receive mail pieces from the upper and lower paths, respectively. Each bin section includes a row of bins and an associated series of tiltable conveyor sections which can be actuated to drop a mail piece into the associated bin. A control system tracks each mail piece as it moves from the scanner to the bins and controls operation of the divert section and the tiltable conveyor section so that each mail piece is sorted to predetermined bin based on the sorting information read by the scanner.
The foregoing mixed mail sorter has proven effective for sorting mail in a variety of thicknesses and sizes. A printer 124 is used to apply of bar codes or other machine readable patterns to the mail pieces as they pass out of the turner module. However, the foregoing mixed mail sorting system has no means of weighing a mail piece as it passes along at the conveyed speed, or of metering mail based on the weight of each mail piece.